The Center for Prostate Disease Research (CPDR) has projected that there will be over 200,000 new cancer cases and 27,000 deaths from prostate cancer in the year 2007. Prostate cancer alone accounts for roughly 29% of cancer incidences in men. According to the National Cancer Institute (NCI), a man's chance of developing prostate cancer increases drastically from 1 in 10,000 before age 39 to 1 in 45 between 40-59 and 1 in 7 after age 60. The overall probability of developing prostate cancer from birth to death being close to 1 in 6.
Traditionally either elevated Prostate Specific Antigen (PSA) level or Digital Rectal Examination (DRE) has been widely used as a standard for prostate cancer detection. For a physician to diagnose prostate cancer, a biopsy of the prostate must be performed. This is done on patients that have either abnormal PSA levels or an irregular digital rectal exam (DRE), or on patients that have had previous negative biopsies but continue to have elevated PSA. Biopsy of the prostate requires that a number of tissue samples (i.e, cores) be obtained from various regions of the prostate. For instance, the prostate may be divided into six regions (i.e., sextant biopsy), apex, mid and base bilaterally, and one representative sample is randomly obtained from each sextant. Such random sampling continues to be the most commonly practiced method although it has received criticism in recent years on its inability to sample regions where there might be significant volumes of malignant tissues resulting in high false negative detection rates. Further using such random sampling it is estimated that the false negative rate is about 30% on the first biopsy. That is, 30% of the men had cancer, but the biopsy procedure missed finding it. Thus, many men will require a second and sometimes a third prostate biopsy, at the discretion of their physician. This can result in increased patient anxiety, health care costs, and/or delayed cancer diagnosis.
Accordingly, to improve the detection of cancer during biopsy, researchers have discussed different sampling schemes as well as using more cores or sampling different regions for improving detection rates. In the latter regard, it has been proposed to obtain samples from additional regions (e.g., 10 core biopsy) not sampled by standard sextant biopsy. Others have noted the difference in cancer likelihood in the different zones of the prostate (e.g. inhomogeneous distribution) and proposed more complete sampling of regions that have a higher likelihood of being cancerous. In addition to studies verifying inhomogeneous spatial distribution of cancers there is also the possibility of cancers occurring in specific regions based on age, PSA level and ethnicity.